Commentary for Makkot 3:6
מנהני מילי א"ר יהושע בן לוי (אמר ר"ש בן לקיש) דאמר קרא (דברים יט, יט) ועשיתם לו כאשר זמם לו ולא לזרעו וליפסלוהו לדידיה ולא ליפסלו לזרעיה בעינן כאשר זמם לעשות וליכא
What is the source? R' Yehoshua ben Levi said (in the name of R' Raish Lakish) And you shall do to him as HE plotted, [meaning] to him, and not to his offspring. [So] then revoke just his priesthood and not his offspring's, [but] the laws of false witnesses requires the same punishment, and it is missing here.
Rashi on Makkot
And not his seed - If you make him illegitimate (for priesthood) and he is (currently) a priest, his offspring will also be disqualified for evermore:
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Rashi on Makkot
We require as they intended (to do to the original accused) - and he (the false witness) was falsely testifying, to disqualify the accused and his offspring:
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